Air bag and air bag apparatus

ABSTRACT

An air bag body ( 1 ) is expanded by charging an air therein after being expanded in a flat surface shape. Next, by gently gripping the air bag body ( 1 ) by upper and lower blades ( 26, 25 ) radially arranged in a radial direction of the air bag body ( 1 ), a height in a radial direction of the air bag body ( 1 ) is linearly restricted along the upper and lower blades ( 26, 25 ). Next, a plurality of movable blocks ( 24 ) are forward moved toward a center of the air bag body ( 1 ), and upper and lower panels ( 12, 11 ) of the air bag body ( 1 ) are accumulated. At this time, the upper and lower panels ( 12, 11 ) of the air bag body ( 1 ) are folded in a state of being apart from each other so as to form a wave shape. Next, the air bag body ( 1 ) is rotated, a portion left in a tab shape is wound around a periphery, and a center protruding portion of the air bag body ( 1 ) is pressed from an upper side, whereby a front surface deploying portion ( 35 ) is formed. When supplying gas to the folded air bag body ( 1 ), the front surface deploying portion ( 35 ) rapidly deploys so as to break a cover ( 5 ) and the gas is smoothly supplied to a peripheral edge portion ( 14 ), whereby it is possible to smoothly and rapidly deploy the air bag body ( 1 ).

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an air bag expanding anddeploying due to an inflow of gas, and an air bag apparatus.

[0003] 2. Description of the Related Art

[0004] Conventionally, there has been known, for example, an air bagapparatus provided in a steering wheel of a motor vehicle. The air bagapparatus is provided with an air bag body formed in a flat bag shape, acover covering the air bag body, an inflator injecting gas, and thelike. Then, the air bag body is folded to be small in accordance with acertain method at unactivated state so as to be received inside thecover. At a time of detecting an impact of collision by a collisionsensor, the air bag body is expanded by injecting the gas from theinflator. The cover is broken due to an expansion pressure of the airbag body and the air bag body is protruded, expanded and deployed toface the passenger, so that the impact of the collision to a passengeris reduced.

[0005] The air bag body has been conventionally folded along a straightline at a predetermined position from a state being expanded on a flatplate so as to be formed in a rectangular parallelepiped shape capableof being received in the cover. However, there is a problem that it ishard to mechanically produce the folded air bag body, a lot of labor isrequired and it is hard to improve the productivity.

[0006] In order to improve the above mentioned points, as a foldingmethod suitable for the automation, for example, there has been known astructure shown in International Patent Publication Laid-Open No.WO97/48580. In particular, the air bag body is expanded by using afolding apparatus provided with a folding plate arranged so as to form acoaxial circle shape or a spiral shape in opposite to each other fromupper and lower portions of the air bag body. The air bag body is foldedby gripping the air bag body by the folding plates, moving or deformingthe folding plates toward predetermined hollow space so as to reduceradial distance between each of adjacent folding plates. However, inthis structure, there is a problem that the structure of the apparatusbecomes complex and it is not easy to reduce the production cost.

[0007] Further, with respect to, for example, the air bag body formed ina flat circular shape, there has been proposed a so-called petal fold inwhich the air bag body is collected toward a center from an outerperipheral portion thereof so as to form a pleat shape. With respect tothis method, there have been known structures described in JapanesePatent Publication Laid-Open Nos. 10-129381, 10-217894 and the like.

[0008] At present, there is required a structure of an air bag bodywhich can improve the deploying characteristic and reduce the productioncost.

SUMMARY OF THE INVENTION

[0009] The present invention is made by taking the points mentionedabove into consideration, and an object of the present invention is toprovide air bag and an air bag apparatus which the deployingcharacteristic is improved and the production cost can be reduced.

[0010] The first aspect of the invention provides an air bag comprising:a first surface portion with an inlet port through which gas isintroduced into the air bag; a second surface portion opposing to thefirst surface portion; wherein the first surface portion and the secondsurface portion are respectively accumulated and folded in a pleats likefold toward the inlet port with being substantially detached from eachother, a plurality of tab portions formed along the inlet port in aspiral shape, the first surface portion and the second surface portionlinearly opposed to each other at the tab portions.

[0011] The second aspect of the invention provides an air bug apparatuscomprising: an air bag body; an accommodating container receiving anfolded air bag and being breakable at a predetermined condition, the airbag comprising: a first surface portion with an inlet port through whichgas is introduced into the air bag; a second surface portion opposing tothe first surface portion; wherein the first surface portion and thesecond surface portion are respectively accumulated and folded in apleats toward the inlet port with being substantially detached from eachother, a plurality of tab portions formed along the inlet port in aspiral shape, the first surface portion and the second surface portionlinearly opposed to each other at the tab portions.

[0012] The third aspect of the invention provides an air bag accordingto aforementioned aspects of the invention, wherein the second surfaceportion is formed in a substantially single layer at a part opposing tothe inlet port of the first surface portion, wherein the second surfaceportion includes a portion opposing to the inlet port of the firstsurface portion and has a front surface deploying portion deployable ina direction to a front side of the air bag, wherein the first surfaceportion opposes to and is substantially detached from the second surfaceportion at a part distant from the inlet port, and wherein the frontsurface deploying portion is accumulated and folded toward the inletport without substantially engaging with the tab portion, and isdeployable in a direction moving apart from the inlet port.

[0013] According to aforementioned aspects of the invention, at the tabportion, the gas is smoothly supplied to an end portion of the tabportion along the linearly opposing portion, and the tab portion isdeployed so as to be rewound. Accordingly, the gas introduced from theinlet port is smoothly supplied to a peripheral edge portion, and thedeploying characteristic of the air bag body is improved. Further, thefront surface deploying portion can rapidly deploy to a side of thebreaking portion immediately after the inflow of the gas, break thecover covering the folded air bag body and efficiently deploy the airbag body.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1A is a perspective view showing one embodiment of an air bagbody in accordance with the present invention, and shows a folded stateof the air bag body;

[0015]FIG. 1B is a cross sectional view showing a state of combining acover with the air bag body;

[0016]FIG. 2 is a partially cutaway view in perspective showing a stateof combining a retainer with the air bag body;

[0017]FIG. 3 is a perspective view of a part of a folding apparatus ofthe air bag body;

[0018]FIG. 4 is a perspective view showing a folding step of the air bagbody;

[0019]FIG. 5 is a perspective view showing a folding step of the air bagbody subsequent to FIG. 4;

[0020]FIG. 6 is a perspective view showing a folding step of the air bagbody subsequent to FIG. 5;

[0021]FIG. 7 is a perspective view showing a folding step of the air bagbody subsequent to FIG. 6;

[0022]FIG. 8 is a cross sectional view along a line I-O-II in FIG. 7;

[0023]FIG. 9 is a cross sectional view showing a folding step of the airbag body subsequent to FIG. 8;

[0024]FIG. 10 is a perspective view showing a folding step of the airbag body subsequent to FIG. 7;

[0025]FIG. 11 is a cross sectional view along a line I-O-II in FIG. 10;

[0026]FIG. 12 is a perspective view schematically showing an outerappearance of the air bag body in FIG. 10;

[0027]FIG. 13 is a perspective view showing a folding step of the airbag body subsequent to FIG. 10;

[0028]FIG. 14 is a perspective view schematically showing an outerappearance of the air bag body in FIG. 13;

[0029]FIG. 15 is a perspective view showing a folding step of the airbag body subsequent to FIG. 13;

[0030]FIG. 16 is a cross sectional view along a line III-III in FIG. 15;

[0031]FIG. 17 is a perspective view showing another embodiment of an airbag body in accordance with the present invention; and

[0032]FIG. 18 is a cross sectional view along a line I-O-II in FIG. 17.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] A description will be given by following embodiments of an airbag and an air bag apparatus in accordance with the present inventionwith reference to the accompanying drawings.

[0034] In FIGS. 1A, 1B and 2, an air bag body 1 is assembled in an airbag apparatus corresponding to an occupant restraint apparatus providedin a boss portion of a steering wheel of a motor vehicle. The air bagapparatus is also called as an air bag module, and is constituted by aretainer 3 formed in a substantially ring shape and provided with a studbolt 3 a in a protruding manner, a base plate corresponding to a memberto be mounted, a breakable cover 5 made of a synthetic resin or thelike, an inflator injecting gas and the like in addition to the air bagbody 1 (some of the constituting members are not illustrated). Adescription will be given below by setting a center side to which theair bag body is protruded, namely, a side of a passenger that is asubject to be protected to an upper side, a front side or a frontsurface side, and setting a side of a vehicle body, that is, a side of asteering shaft to a lower side, a rear surface side or a back surfaceside. Further, the air bag apparatus protects the passenger from animpact of collision by injecting the gas from the inflator, expandingthe air bag body 1 received in a folding manner, breaking the cover 5along a predetermined tear-line due to an expansion pressure of the airbag body 1 so as to protrude the air bag body 1, and widely deployingthe air bag body 1 in front of the passenger.

[0035] As shown in FIG. 2, the air bag body 1 is formed in a flat bagshape by sewing two circular base fabrics having substantially the sameshape. That is, the air bag body 1 is formed by overlapping a lowerpanel (a lower base fabric panel) 11 provided with a gas introductionsurface corresponding to a first surface portion and an upper panel (anupper base fabric panel) 12 corresponding to a surface opposing to thegas introduction surface corresponding to a second surface portion,sewing a peripheral edge portion 14 and making it inside out through aninlet port 15 for inserting the inflator, the inlet port 15 having acircular hole shape and formed in a center of the lower panel 11. Thediameter of a hole in a center of the retainer 3 is substantially equalto that of the hole of the inlet port 15. Further, a plurality ofmounting holes 16 into which the stud bolts 3 a are inserted are formedon the lower panel 11 at positions around the inlet port 15corresponding to a gas introduction port through which the gas isintroduced by the inflator. Apart of the lower panel 11 around the inletport 15 is reinforced by an annular reinforcing fabric 18. Single or aplurality of vent-hole (not shown) for ventilating the gas introduced bythe inflator is formed on the lower panel 11. In the present embodiment,each of the panels 11 and 12 is formed by a so-called “non-coat” basefabric having a diameter of 650 mm, using a yarn of 66-nylon and 315denier with 200 g/m2 and having no elastomer coatings, for example.

[0036] As shown in FIGS. 6, 7 and 13, the folding apparatus 21 isconstituted by a table 22, a center block 23 corresponding to expandingmeans and pressing means, a plurality of movable blocks 24 correspondingto accumulating means, a lower blade 25 and an upper blade 26corresponding to a guide member, a center plate 27 corresponding todisplaciing means, control means (not shown) controlling these elements,an electric power source apparatus, a drive source and the like.

[0037] The table 22 is provided with a substantially flat plate surface(hereinafter, the plate surface of the table 22 is referred as areference surface S) on an upper surface thereof, and as shown in FIG.3, a center block 23 is placed in a circular hole 22 a provided in acenter portion of the plate surface. The center block 23 is providedwith a circular column portion 23 a having a shape similar to theinflator and a peripheral edge portion 23 b surrounding the circularcolumn portion 23 a and coaxially provided at a position lower than thecircular column portion 23 a. Further, the center block 23 is structuredsuch that a rotating mechanism rotating at an optionally set angle up toabout 90 degrees and a vertically moving mechanism vertically moving atan optionally set stroke up to about 160 mm are combined. An air nozzle(not shown) injecting the air is installed in the center block 23.Holding portions 23 c each having a circular hole shape and capable ofinserting the stud bolt 3 a of the retainer 3 so as to fix are formed inthe peripheral edge portion 23 b at a predetermined interval. In thiscase, in the respective drawings, for explanation purpose, the table 22and the center block 23 are omitted.

[0038] As shown in FIG. 3, a plurality of slit portions 22 b areradially formed around the circular hole 22 a on the table 22, and alower blade 25 having a flat plate shape and being vertical to thereference surface S is provided in each of the slit portions 22 b insuch a manner as to move forward and backward in a vertical direction,more particularly, in such a manner as to move from the plate surface ofthe table 22 to a predetermined height. Further, a guide portion 25 aparallel to the reference surface S is provided in each of the lowerblades 25 along an upper end edge portion. An end portion of the guideportion 25 a, that is, a corner portion between an inner peripheral sideand an outer peripheral side of each of the lower blades 25 is formed ina smooth curved surface.

[0039] As shown in FIG. 7 for example, movable blocks 24 arerespectively provided at a position between the lower blades 25. Each ofthe movable blocks 24 is connected to driving means arranged under thetable 22 via a slit (not shown) provided on the table 22, and is guidedand driven so as to move forward and backward from the peripheral edgeportion of the table 22 to a portion near the center block 23, that is,each of the movable blocks can be collected and distributed. Further,each of the movable blocks 24 is formed in a substantially fan shape inplan, and a pressing portion 24 a is provided in an end portion in theinner peripheral side thereof opposing to the center block 23, forexample, in a curved surface shape.

[0040] A plurality of upper blades 26 are radially mounted on a lowersurface of an upper plate 29 provided above the table 22 as shown inFIG. 6, and are moved and driven forward and backward in a verticaldirection together with the upper plate 29. Further, each of the upperblades 26 is arranged so as to oppose to the lower blade 25, a pair ofcorresponding upper and lower blades 26 and 25 have an opposing line atthe end edges. A pair of upper and lower blades 26 and 25 arealternately arranged with the movable block 24 in a circumferentialdirection. The upper blade 26 has a plate shape, which is similar to thelower blade 25, vertical to the reference surface S, and an end portion,that is, a corner portion thereof has a smooth curved surface shape.Further, a guide portion 26 a parallel to the guide portion 25 a of thelower blade 25 is formed in the upper blade 26 so as to oppose to theguide portion 25 a. A length of each of the upper blades 26 issubstantially the same as that of the lower blade 25, however, a heightthereof is formed to be larger than that of the lower blade 25. Theupper plate 29 is provided with support portions 29 b supporting each ofthe upper blades 26 and arranged so as to form a radial shape in plan,an inner peripheral side connecting portion 29 c connecting end portionsin an inner peripheral side of the support portions 29 b to each other,and an outer peripheral side connecting portion 29 d connecting endportions in an outer peripheral side of the support portions 29 b toeach other.

[0041] In this case, an emboss work is applied to end portions 26 a and25 a at which the upper and lower blades 26 and 25 are linearly incontact with the air bag body 1, or an elastomer tape or the like isadhered thereto, whereby these portions are slidably contact with theair bag body 1 with a suitable sliding resistance.

[0042] In accordance with the present embodiment, eight movable blocks24 and eight pairs of upper and lower blades 26 and 25 correspondingthereto are provided. In the case of the structure which does not coverthe above of the inlet port 15 of the air bag body 1, the number ofthese elements can be suitably selected with taking a capacity of theair bag body 1 and a shape of a space in which the air bag body 1 isreceived.

[0043] Further, a circular hole 29 a is pierced in the center portion ofthe upper plate 29, and a disc-like center plate 27 (refer to FIG. 13)having substantially the same diameter as that of the circular hole 29 aand vertically driven independent from the upper plate 29 is arrangedwithin the circular hole 29 a.

[0044] Next, a description will be given of a folding step of the airbag body 1 with reference to FIGS. 1A to 16. In this case, in FIGS. 3 to6, the movable block 24 is omitted.

[0045] In an initial state, the center block 23 is arranged so that aback surface of the peripheral edge portion 23 b is connected parallelto a front surface of the table 22, as shown in FIG. 3. Further, thelower blade 25 is retracted downward from the back surface of the table22, the upper blade 26 and the center plate 27 are retracted upward andthe movable block 24 is retracted to the outer peripheral side. On thecontrary, with respect to the air bag body 1, as shown in FIG. 2, theretainer 3 is previously inserted into an inner portion of the air bagbody 1 from the inlet port and the stud bolt 3 a is taken out from themounting hole 16, as shown in FIG. 2. After the above mentioned state,the air bag body 1 is expanded on the table 22 so as to form a flatplate and set in a stationary manner, as shown in FIG. 4, and thecircular column portion 23 a of the center block 23 is inserted into theinlet port 15. Further, each of the stud bolts 3 a is inserted to theholding portion 23 c and is fixed by a lock mechanism (not shown)provided in the holding portion 23 c.

[0046] Next, as shown in FIG. 5, as an expanding step in the restrictingand expanding step, a compressed air is bled into the air bag body 1from an air nozzle, as shown by an arrow A, provided in the circularcolumn portion 23 a of the center block 23 so as to form the air bagbody 1 in an flat cushion shape. Here, in this state, the air bag body 1is in a state of being expanded so as to be softer than a hardness ofthe air bag body 1 in a complete expanding state such as the state at atime of deploying the air bag body 1.

[0047] Next, as shown in FIG. 6, as a restricting step in therestricting and expanding step, as well as the lower blade 25 isascended and protruded upward from the surface of the table 22, theupper blade 25 is descended so as to be brought into contact with theair bag body 1. Further, as shown in FIGS. 7 and 8, the air bag body 1is held between the lower blade 25 and the upper blade 26 so as to beradially depressed. In this state, a predetermined interval is setbetween the guide portions in the upper and lower blades 26 and 25, andthe air bag body 1 is partly restricted in the height direction, and isslidable in the radial direction. After this state, when increasing theinternal pressure of the air bag body 1, the upper blade 26 whichcontacts with the expanding air bag body 1 protrudes upward so as tomove the upper and lower panels 12 and 11 apart from each other,however, the upper plate 29 is kept at a height at which the upper panel12 of the air bag body 1 is not in contact therewith.

[0048] Next, as an accumulating step, each of the movable blocks 24 isinterlocked and is moved forward so as to be gathered toward the centerpoint O at the same time. Each of the blocks 24 moves to the forwardmovement limit shown in FIGS. 10 and 11 via an intermediate state shownin FIG. 9. In FIG. 9 schematically showing the air bag body 1 in themiddle step of the folding, the air bag body 1 is structured such thatthe upper and lower panels 12 and 11 are folded so as to form a waveshape without substantially engaging with each other, that is, in aso-called “estranged” from each other in the portion pressed by themovable block 24, and an expanding portion 31 protruding so as to form adome shape is formed in the center. A plurality of wave-like recessportions 32 are formed in the periphery of the expanding portion 31. Aplurality of tab portions 33 are formed in a portion gripped between theupper and lower blades 26 and 25. Accordingly, a whole shape of the airbag body 1 is formed in a substantially asterisk shape. In this case, inaccordance with the forward movement of each of the movable blocks 24,each of the tab portions 33 slides toward the center portion through theportion between the blades 26 and 25 together with the wave-like recessportion 32 corresponding to the accumulated portion, so that theexpanding portion 31 tends to be further protruded.

[0049] Next, as shown in FIG. 13, as a restriction reducing step, theupper blade 26 is set at the current position, and the lower blade 25 isretracted slightly downward or wholly. Accordingly, it is possible toweaken or do away with the force gripping the linearly guided tabportion 33 of the upper and lower panels 12 and 11, and is possible tokeep the shape of the air bag body 1 by the center plate 27 and themovable block 24. In this case, in the restriction reducing step, it maybe adopted to move the upper blade 26 upward at a slight amount.

[0050] Next, as shown in FIG. 13, as a pressing step, the center block23 holding the >center portion of the air bag body 1 is rotated in adirection shown by an arrow C at a predetermined angle. Together withthis rotation, the tab portion 33 is taken into the pressing portion 24a side of the movable block 24, and is arranged along the outerperiphery portion of the wave-like recess portion 32 so as to form aspiral shape. The tab portion 33 is arranged therealong without beingdeformed upward by the upper blade 26, and the shape of the folded airbag body 1 is arranged at a predetermined height.

[0051] As a displacing step after the accumulating step, the centerplate 27 is descended. As shown in FIGS. 15 and 16, the expandingportion 31 expanding above the air bag body 1 is pressed down andaccumulated so as to form in a flat shape. A front surface deployingportion 35 not engaging with the other portions is formed by coveringthe expanding portion 31 formed in a flat shape over the folded portionof the air bag body 1, and is restricted to a height corresponding to apredetermined receiving size. After this state, as shown in FIG. 1A, theair bag body 1 is folded in a predetermined shape having a substantiallypetal shape, and the shape of the air bag body 1 is arranged in a columnshape of a substantially regular octagon in plan view having apredetermined height.

[0052] When the air bag body 1 folded in the manner mentioned above isassembled in the air bag apparatus, the inflator is operated and the gasis supplied from the inlet port 15 of the air bag body 1, at first thefront surface deploying portion 35 positioned immediately above theinlet port 15 is rapidly deployed to the front surface side, and breaksthe cover 5 so as to form the protruding port.

[0053] Next, the upper and lower panels 12 and 11 are easily moved apartfrom each other, and the tab portion 33 arranged along the outerperiphery of the wave-like recess portion 32 in the folding final stepis pressed to the outer peripheral side, whereby the air bag body 1 canbe rapidly deployed. Further, the supplied gas is smoothly suppliedalong the portion restricted by upper and lower blades 26 and 25linearly opposing to each other to the end portion of the tab portion33, and the tab portion 33 is deployed so as to be rewound, whereby itis possible to easily improve the deploying characteristic.

[0054] In the folding apparatus 21 in accordance with the presentembodiment, the portion corresponding to the upper blade 26 in the upperpanel 12 of the air bag body 1 is linearly guided by the upper blade 26along a track accumulated by the movable block 24. The structure is madesuch that the other portion than the portion corresponding to the upperblade 26 in the upper panel 12 can freely protrude without beingrestricted in height. Since the whole surface of the upper panel 12 isrestricted in height, the structure of the air bag body 1 can be madesimple, and it is possible to sufficiently move the upper and lowerpanels 12 and 11 apart from each other at a time of expansion. Further,in the state that the air bag body 1 is folded, it is possible to makethe upper and lower panels 12 and 11 not be engaged substantially witheach other from the inlet port 15 to the peripheral edge portion 14.

[0055] Since the upper and lower blades 26 and 25 are retracted and thecenter block 23 is rotated after the accumulating step of moving forwardeach of the movable blocks 24, it is possible to reduce the forceapplied to the upper and lower panels 12 and 11 and it is possible tosmoothly fold the air bag body 1.

[0056] Since the front surface deploying portion 35 provided in thecenter front surface of the air bag body 1 deploys at the beginning soas to rapidly break the cover 5, it is possible to effectively utilizethe pressure of the gas injected from the inflator so as to intend torapidly deploy the air bag body 1, and it is possible to intend to makethe air bag apparatus compact. Since it is possible to reduce theprimary peak pressure of the injection gas, it is possible to increasethe secondary peak pressure of the injection gas and it is possible toeffectively utilize the gas pressure of the inflator. At a time ofdeploying the air bag body 1, the air bag body 1 is deployed so that theexpanding portion 31 can be reformed due to the gas pressure from thefront surface deploying portion 35, and the front surface deployingportion 35 can smoothly break the cover 5 formed by using a soft resinor the like. Further, it is possible to easily adjust the passengerrestraining characteristic by reducing the internal pressure (theprimary pressure), reducing the impact and deploying in the peripheraldirection, in accordance with the deployment of the front surfacedeploying portion 35.

[0057] As mentioned above, in accordance with the air bag body 1 and theair bag apparatus using the air bag body 1 of the present embodiment, itis possible to rapidly deploy and it is possible to easily improve thedeploying characteristic. Further, in accordance with the method offolding the air bag body 1 suitable for automation and the foldingapparatus 21 to which the method of folding the air bag body 1 isapplied of the present embodiment, it is possible to reduce theproduction cost of the air bag body having the improved deployingcharacteristic and it is possible to inexpensively provide the air bagbody.

[0058] In accordance with the embodiment mentioned above, with respectto each of the lower blade 25 and each of the upper blades 26, the guideportions 25 a and 26 a parallel to each other are provided, however, itis possible to change the shape of the guide portion so as to intend tosmoothly guide the air bag body 1 in the folding step.

[0059] For example, as in a folding apparatus 21 shown in FIGS. 17 and18, with respect to the lower blade 25, there are provided with a firstguide portion 25 b in which an upper end edge portion thereof isparallel to the table 22 front surface, and a second guide portion 25 cdescending from an inner peripheral side end portion of the first guideportion 25 b toward an inner peripheral side so as to form an inclinedsurface. On the contrary, with respect to the upper blade 26 having aheight wholly larger than that of the lower blade 25, there are formed afirst guide portion 26 b opposing to the first guide portion 25 b of thelower blade 25 and being parallel to the first guide portion 25 b, and aparallel second guide portion 26 c opposing to the second guide portion25 c of the lower blade 25. Further, in the second guide portion 26 c, asurface parallel to the surface of the table 22 is provided incontinuous with the inclined surface inclined toward the upper side, andis arranged so as to protrude to an inner peripheral side from the lowerblade 25. In this case, to the first guide portions 26 b and 25 b andthe second guide portions 26 c and 25 c corresponding to end portions atwhich the upper and lower blades 26 and 25 are linearly in contact withthe air bag body 1, an emboss work is applied or an elastomer tape orthe like is adhered, whereby it is set that they are slidably in contactwith the air bag body 1 with the proper sliding resistance.

[0060] In each of the embodiments mentioned above, after theaccumulating step of forward moving each of the movable blocks 24 andthe pressing step of rotating the center block, the displacing step ofdescending the center plate is executed. On the contrary, the structurecan be made such that after the accumulating step of forward moving eachof the movable blocks 24, the displacing step of descending the centerplate is executed so as to form one upper panel 12 in a substantiallyflat surface shape at the portion opposing to the inlet port 15 of thelower panel 11 and next, the pressing step of rotating the center block23 is executed, thereby folding the air bag body 1. In this structure,the upper panel 12 is arranged by one sheet in a substantially flatsurface shape without being folded, at the portion opposing to the inletport 15 of the lower panel 11. Accordingly, the gas introduced from theinlet port 15 is smoothly supplied to the outer peripheral side from theportion near the inlet port 15, and it is possible to intend to smoothlydeploy the folded wave-like recess portion 32 and the tab portion 33toward the outer peripheral side.

[0061] Further, in each of the embodiments mentioned above, in therestricting and expanding step, the height of the air bag body 1 isrestricted by the upper and lower blades 26 and 25 after expanding theair bag body 1. In addition to the structure mentioned above, it ispossible to employ an operating step of expanding the air bag body 1after restricting the height of the air bag body 1 by the upper andlower blades 26 and 25, and an operating step of restricting the heightof the air bag body 1 by the upper and lower blades 26 and 25 whileexpanding the air bag body 1.

[0062] The present invention mentioned above can be applied to an airbag apparatus for a passenger in an assistant driver's seat provided inan instrument panel, an air bag apparatus for a side protection providedin a side portion of a seat or a door and a pillar of a vehicle body, anair bag apparatus for a rear passenger provided in a rear portion of theseat, the other air bag apparatuses for protecting a subject to beprotected from an impact, and the like, in addition to the air bag bodyfor the air bag apparatus provided in the steering wheel of the motorvehicle.

What is claimed is:
 1. An air bag comprising: a first surface portionwith an inlet port through which gas is introduced into said air bag; asecond surface portion opposing to said first surface portion; whereinsaid first surface portion and said second surface portion arerespectively accumulated and folded in a pleats like fold toward saidinlet port with being substantially detached from each other, aplurality of tab portions formed along said inlet port in a spiralshape, said first surface portion and said second surface portionlinearly opposed to each other at said plurality of tab portions.
 2. Anair bag as claimed in claim 1 , wherein said second surface portion isformed in a substantially single layer at a part opposing to said inletport of said first surface portion.
 3. An air bag as claimed in claim 1, wherein said second surface portion includes a portion opposing tosaid inlet port of said first surface portion, and has a front surfacedeploying portion deployable in a direction to a front side of said airbag.
 4. An air bag as claimed in claim 1 , wherein said first surfaceportion opposes to and is substantially detached from said secondsurface portion at a part distant from said inlet port.
 5. An air bagapparatus as claimed in claim 3 , wherein said front surface deployingportion is accumulated and folded toward said inlet port withoutsubstantially engaging with said tab portion, and is deployable in adirection moving apart from said inlet port.
 6. An air bag apparatuscomprising: an air bag body; an accommodating container receiving anfolded air bag and being breakable at a predetermined condition, saidair bag comprising: a first surface portion with an inlet port throughwhich gas is introduced into said air bag; a second surface portionopposing to said first surface portion; wherein said first surfaceportion and said second surface portion are respectively accumulated andfolded in a pleats like fold toward said inlet port with beingsubstantially detached from each other, a plurality of tab portionsformed along said inlet port in a spiral shape, wherein said firstsurface portion and said second surface portion linearly oppose to eachother at said plurality of tab portions.
 7. An air bag apparatus asclaimed in claim 6 , wherein said second surface portion is formed in asubstantially single layer at a part opposing to said inlet port of saidfirst surface portion.
 8. An air bag apparatus as claimed in claim 6 ,wherein said second surface portion includes a portion opposing to saidinlet port of said first surface portion, and has a front surfacedeploying portion deployable in a direction to a front side of said airbag.
 9. An air bag apparatus as claimed in claim 6 , wherein said firstsurface portion opposes to and is substantially detached from saidsecond surface portion at a part distant from said inlet port.
 10. Anair bag apparatus as claimed in claim 8 , wherein said second surfaceportion includes a portion opposing to said inlet port of said firstsurface portion, and has a front surface deploying portion deployable ina direction to a front side of said air bag.